Manual Order - automated tax calc / add

I'd like to have an enhancement at the "add order" button in the backend.

At the moment, i have to calculate and to enter the tax(es) manually. Yes it works, but it is not very comfortable and maybe, one makes a mistake...

I sell food an nonfood, so i have two tax classes, 7 and 19%.
It would be nice to take the tax from the product itself, if i add an product from my articles and an additional field to enter the tax - or a dropdown with my stored tax classes - if i enter a non-stored product.
If i choose an product from my stored articles, the field should be auto-filled, so i can see the tax rate.
And then, the form should show all tax classes and the calculated tax amount per class.

For example. i choose a product with 19% for 100€ net and a product with 7% for 50€ net, it should add the tax fields 19% with 19.00€ and the tax field 7% with 3,50 €.

It is almost perfect, but i miss a column "tax rate". I still have to calculate taxes for articles not stored in the database - such as manually added articles. and so, i have two times the 19% or 7% in my order